New optogenetic research on mice from Karl Deisseroth’s lab at Stanford has identified two important pathways related to anxiety control in the brain. The lab has pioneered a technique that genetically modifies specific cells to become more active when light is introduced. This way the researchers are able to pinpoint which cells are involved with a specific brain activity.
From National Science Foundation’s press release:
Directed genetic manipulations cause specific neurons to assemble a light-activated protein normally found in algae and bacteria. When triggered by certain wavelengths of light, these proteins allow researchers to increase or decrease neuronal activity in the brain and observe the effects on rodent models in an experiment.
Using optogenetic manipulation of various amygdala pathways, Deisseroth and colleagues examined how mouse behavior was affected. Since mice display anxiety-related behaviors in open spaces, they measured changes in anxiety by analyzing how much time mice spent exploring the center of an open field, or exploring the length of a platform without walls.
While optogenetics has been used to study amygdala function in behaviorally-conditioned fear, this is the first time it has been used to study anxiety. “Fear and anxiety are different,” Deisseroth explained. “Fear is a response to an immediate threat, but anxiety is a heightened state of apprehension with no immediate threat. They share the same outputs, for example physical manifestations such as increased heart rate, but their controls are very different.”
Press release: Researchers Selectively Control Anxiety Pathways in the Brain
Abstract in Nature: Amygdala circuitry mediating reversible and bidirectional control of anxiety
Medgadget’s previous coverage of optogenetic research from Deisseroth’s lab: Pentagon Seeks to Repair Brains with Optogenetic Implants; fMRI Gains Validation from Optogenetics; Fiber Optics Activate Neurons, Axons to Answer Parkinson’s Questions; Scientists Optically Deconstruct Parkinsonian Neural Circuitry